The main goals of this research project are: 1) To evaluate the functional and morphological characteristics of human vascular endothelial and smooth muscle cells in vitro and to compare those obtained from adult and fetal arteries and veins on their response to atherogenic stimuli. 2) To investigate by cytochemical and ultrastructural techniques the early stages of arterial repair following reproducible and rapidly resslving vascular injury induced by non-invasive techniques under development in our laboratory. 3) To study in detail the role of lipoproteins and platelets on arterial repair during the progression or regression phases of experimental atherosclerosis.